Estimation of Cortical Components in Various Wools

Abstract

Wools varying widely in diameter and crimp. from sheep of several breeds and ages.were stained with various reagents chosen to give high contrast between ortho-and paracortical segments. The brown to black sulfide stain produced in wools by sodium plumbite, selective for the paracortex, was measured quantitatively and observed to increase with diameter. The greatest rate of change occurs in the fine diameter region. Wools shorn from sheep at different ages show lead sulfide staining increasing with age at shearing. Wool fibers which have been elongated or supercontracted show increased staining, which reflects the mechanical damage. The same wools were stained with acid nickelous nitrite, preferentially staining the ortho segment. It was verified that in this case the order of staining of the various wools is the reverse of that with plumbite. Solubility in an aqueous solution of urea and monothioglycol is shown to increase regularly with the degree of staining in the nickel solution. Bromine water also preferentially stains the orthocortex. Finally, paralleling the staining behavior, the stress in wool at 30% extension (wet) increases generally with diameter as well as with increasing maturity of the sheep..

Crimp in Wool: Cortical Segmentation and Tensile Properties of Well-Crimped and Abnormally Crimped Fibres of Merino Wool

“…The larger percentages of para cortex in the group with the larger fibre thicknesses are then in agreement with Ahmad and Lang (1957), with Thorsen (1958), and also with the present study in which the poorly crimped fibres are thicker than the well-crimped fibres (Chapman and Short 1964). From these various studies it becomes apparent that the percentage of para cortex is dependent on fibre thickness rather than on crimp frequency.…”

“…Disposition of the cortical segments, on the other hand, is related to crimp form (Fraser and Rogers 1953;Horio and Kondo 1953;Mercer 1953;Ahmad and Lang 1957;Glynn, Lang, and Wardle 1960;and present results), and to some extent to fibre thickness (Fraser and Rogers 1955;Ahmad and Lang 1957;Thorsen 1958). Poorly crimped fibres exhibit segmental distributions not observed in well-crimped fibres (see Section III), and are produced by follicles with gross irregular enlargements of the outer root sheaths adjacent to the supra-bulbar and keratogenous zones of the fibres (Chapman, Short, and Hyland 1960).…”

“…By contrast, the percentage of paracortex increases with increase in crimp frequency in samples of Merino wool with reversed relationships of crimp frequency to fibre thickness (Snyman 1963). The proportion of para cortex increases also with fibre thickness within breeds (Ahmad and Lang 1957;Thorsen 1958;Snyman 1963) and to some extent between breeds (Thorsen 1958).…”

“…For fibres separated on the basis of crimp frequency per unit of fibre length from within staples of Suffolk, Rambouillet, and Navajo wools, Young's modulus and stress at 30% extension in water increase with decrease in crimp frequency (O'Connell and Yeiser 1954). An increase in the stress at 30% extension in water also accompanies an increase in percentage of para cortex (Thorsen 1958). In agreement with this, reduced mechanical stiffness is exhibited after removal by abrasion of the outer para-like portion of Lincoln wool fibres with a radial distribution of ortho-and paracortices (Feughelman and Haly 1960).…”

Using Electron Microscopy and X-Ray Microanalysis to Study Wool Morphology and Composition

“…Hence the precise component producing the detected x-rays cannot be determined. In the STEM, the very thin sections required for maximum resolution of components give very low intensities of x-rays because of the much smaller specimen volumes.The merino wool fiber consists of an inner cortex and a peripheral region known as the cuticle [3,15].The cortex can be differentiated into orthocortical and paracortical cells on the basis of the denser staining of the orthocortex by basic dyes, acid dyes, and phosphotungstic acid, and by salts of lead, mercury, silver and gold [2,5,10,12,16,21 ]. Several attempts have been made to determine the origin in the intact wool fiber of various proteins isolated as soluble extracts [3,6].…”